Lamp socket



Feb. 8, 1944. H. N. FAIRBANKS LAMP SOCKET Filed June 22, 1942' INVENTOR@W A TTORNEYS Patented ch. 8, 1944 LAMP socxn'r Henry N. Fairbanks,Rochester, N. Y., assignor'to Eastman Kodak Company,

Rochester, N. Y., a

. corporation of New Jersey Application June 22, 1942, Serial No.441.9147 8 Claims. (CI. 88-24) The present invention relates to lampsockets of the type wherein a lamp is adapted to be inserted thereintoby a straight thrust as distinguished from screw sockets, andparticularly to the combination of such a socket with a pictureprojecting apparatus.

As is well known, it is common practice to provide sockets for electriclamps into which the lamp is inserted by a straight thrust and thengiven a partial turn to lock it in place therein. These sockets arecommonly referred to as bayonet type sockets and are adapted to receivelamps having a complementary bayonet type base. contact in the center ofthe base thereof adapted to engage the central contact in the base ofthe lamp, and the resiliency oi this contact in the socket opposes theinsertion of the lamp into the socket. This contact in the socket ismade resilient for two reasons. First, it forms an important part ofthebayonet type lock in that it acts to hold the parts in lookingrelationship after the lamp has been partially rotated to establish therelationship. Secondly,- it insures a good electrical contact betweenthe socket contact and the contact in the base of the lamp.

When lamp sockets of this type are used on apparatus which is subject tovibration and Jars it has been found imperative to place a strong springbehind the contact in the lamp socket in order to prevent the lamp fromjarring from a locked relationship in the socket, to hold the lampagainst any vibration, and to insure a good contact between the. socketcontact and the lamp contact at all times. The strength of the springnecessary behind the base contact of a socket of the type set forth willvary with the particular application of the socket. v

In order to insert a lamp into a socket of the type in question it isnecessary to thrust the same into the socketagainst the opposition ofthe spring contact by grasping the glass globe of the same. In caseswhere strong springs have been required in sockets it has been foundthat the force required to place the lamp in the socket has beensumcient to break the glass globe of the lamp. As a result. a lamp whichmight be expensive is wasted and there is a verygood chance that theperson's hand is cut in the operation. Even if the thrust required ininserting a lamp into such a socket is not in fact suihcient to breakthe lamp globe, it is often suiilcient to make a person wary of changinga lamp in the socket for fear it will break. In addition, when one iscompelled to firmly grip a Sockets oi.this type include .a resilient hotlamp, probably burned out, in order to remove it from its socket he isliable to get a painful burn. It is also significant that lamp socketsoi the type in question are very often mounted in rather inaccessibleplaces so that in order to insert a lamp therein the lamp globe must begripped at the extreme end by the tips of the fingers only withv theresult that the thrust necessary to insert the lamp into the socket mustbe transmitted throughout the entire length of the lamp globe.

Therefore, the primary object of the present invention is the provisionof a lamp'socket into which'a lamp is adapted to be inserted by astraight thrust in opposition to a resilient contact in the base of thesocket after which it is adapted to be locked in said socket by theengagement of cooperating parts on the lamp base and socket shell andmeans for purposely decreasing the resilient force of said contact priorto changing a lamp in the-socket and again increasing the resilientforce of said contact after the lamp is changed and'is ready for use.

Another object is the provision of a socket of the type set forth whichis movable between two positions, a lamp changing position and aproiecting position, and including means for automaticalLv decreasingand increasing the resilient force of the socket contact as the socketis moved to and from said lamp changing position, respectively.

A further object is the provision of a socket of the type set forthwherein the circuit to the socket is automatically broken when the sameis moved to said lamp changing position and automatically completed whenreturned to the projection position so that a person ha alamp is notstartled by lighting up of a lam during its insertion into the socket.

Andyet another object of the present invention is the provision ofa-socket of the type set forth which includes a contact havingsuflicient resiliency to initially locate a lamp in the socket andpermit easy insertion of the lamp thereinto, and the resiliency of whichcontact is augmented by the resiliency of asecond contact when thesocket is moved to its projecting po ition.

Another object is to have the socket mounted on a lamp house door of apicture projector so that opening and closing of, the door moves thesocket between its lamp changing and projecting positions,respectively.- i v The novel features that I consider characteristic ofmy invention are set forth with particu- 2 s,s41,4s1 larity in theappended claims. The invention socket for the projection lamp It is oneoi-the itself, however, both as to its organization and bayonet type andinto which the lamp is adapted its methods of operation, together withaddito be inserted by a straight thrust and alter tlonai objects andadvantages thereof, will best which the lamp is given a partial turn 'tolock be understood from the following description oi 5 the same in thesocket. As shown, the lamp specificembodim ts hen readinconnectionsocketmaycompriseacylinderll-ofanysuitwith the A drawing in which. ableinsulating material, such as porcelain, hard .Fig. 1 is a sideelevational view, on reduced rubber, etc., having a circular recess llinto scale, of a well known type motion picture appa which the base of alamp is adapted to be'inratus in combination with the lamp'house of i0serted. The circular recess I! is lined with whichthesocketconstituting'the present inven-- metal shell I. the upper ends of whichare 'tion hasbeen shownfor the purpose of illustrat- 4 formedin'theshape 0! a u as indicated at in: one application oi the same, toterm a partgoi a bayonet lock. Looking at Fig. 2 is an enlarged partialsectional view. of Fig. 4 it will be noticed that the inturned edge thelamp house of the proiectorshown in Fig. 1, it of the shell II isprovided with two diametrically showing how a socket constructed inaccordance opposed arcuate slots 2|. These slots are comwith oneembodiment oi the present invention plementary in shape to twodiametrically opmight be mounted on' the lamp house door, and posedwings 22 on the lamp base 23 so that when showing the lamp house doorclosed, the wings on the lamp base are lined up with F18- 3 i B Vi w Sir t Fis- 2 u showin '20 the arcuate slots the lamp base may be insertedthe lamp house door opened and the socket into the socket after whichapartial turn of moved therewith to a lamp changing position, the lamprelative to the socket will prevent the P18. 4 is a plan View "of thelamp socket with lamp ircm being pulled from the socket.

the lamp removed and showing the manner of slidably extending through abore II in the mounting it on the lamp h u 1. and 25 bottom oi thesocket is a contact 2! including Fig.; 5 is a top plan view oi the liveresilient a cap 21 located in the socket recess and a stem contactmounted on the-base of the lamp house. at extending beyond the base ofthe socket and reference characters refer to correspondbeing slidablyguided by a sleeve bearing ll fixed par throu hout the drawing. in thebase of the socket. The contact 28 is nor- Generally. he presentinvention comprises a so mally forced into the socket recess by a coiledlamp socket into which a lamp is adapted to be spring II encircling thestem is of the contact inserted by a straight thrust against the oppoandbeing held under compression between the sition of a resilient contactafter which it is cap of the plunger. and a fixed part of the socket.locked in said socket by the combined coopera-- as clearly shown inFigs. 2 and 3.

t on of ensasins pa on t e so s e a 85 Itwillbereadilyappreciatedthatwhenalamp lamp base and theresilie'nt force oi the contact. isinserted mum e the t me 1| The structure is such that the resilientforce 0! 1 th as thereof contacts th cap 21 of the the contact my beurposely reduced to a minicontact 2! and that the spring so op oses itsmum to facilitate changing a lamp on the so ket insertion into thesocket. This spring, however, and may thereafter be urposely increasedto 4 is comparatively light, being of only sufiicimt firmly o he la p it soc t dur s strength to initially hold the lamp in looking lection.The structure is so arran ed that h n relation with the socket, and doesnot alter the the resilient 'iorce oi the-socket contact is reoppositionto the insertion of the lamp-which duced 'the circuit to the socket isautom ica known resilient contacts do which are relied upon broken.'and'when the resilient force is ag in 45 to exert the full force required tofinally position increased the circuit to the so is 8 a lamp in itssocket under operating conditions.

pleted: v A stop pin 32 extending radially through'the librypurp m ofdiscloms the op r i and end of the stem It prevents the contact 2| iromotasocketconstructedinaccordbeinspropelledfromthesocketbythespringaance'with the present'invention I have chosen when a lamp is removedfrom the socket.

to show the same in' com in t n with a The socket may be attached to theinside of the known type of motion picture .appmt B lamp house door ilin any manner to move heever, it will be readily appre ilt b! n sk etween two positions when the door-is open d and in the art that thesocket oi the present invenclosed. To facilitate a final focusing of thelamp tion is not limited to the specific application relative to thepicture strip moving through the ber of diiferent apparatus. bracketincludin spaced cars 84 piv- Referring nowto the drawing, the motionD16", otedto lugs "on thelamp house door Ascrcwtureproiectorshowninl'ig.1isoneofaw fliimedtotheiamphousedoorextendsthmhThelamphouseenclosesaprojectionlampthe iectlonapertureacrosswhichthefilmpa-eeraysofwhichpassthroughthefilmuitmssnisGravitymaybereliedupontoholdtheupstandthefilmgateandtoandthroughaproiectioningarini'lotthebracketagainsttheadimtinl lenslttoasuitablescreen.showmoneside nutaorasprinmnotshowmmaybemoimtedwallofthelamphouseilispivotedtothebotatthepivotpomtcisaidbrackettomrmallytomottfielamphouse,asshownatit,rlgs.2pivotitinaclockwisedirectimiookingatrlea.

andstoiormadoorllwhichcanbeopened 1o2and3.

44, mounted on a locating stud 45 in the bottom wall of the lamp house,i held under compression between the underside of the free end of saidcontact 4| and a shoulder on said stud. Looking at Fig. 3, when the lamphouse door is opened to change a lamp in the socket the only dependentupon the resilient force of the contact tending to puslfthe lamp-fromthe socket.

spring tending to force the contact 26 into the It is believed that thenovel features and advantages of the present socket construction will bereadily apparent from the above description thereof. By way ofsummation, it will sumce to say that the present socket constructionprovides the necessary strong spring in the socket for holding the lampfirmly against movement due to vibrations or jars, and at the same timepermits the force of the spring to be purposely released to facilitatethe insertion of a 28 engages the free end of contact 4| and causes aretraction, or compression, of the spring 44. Thus, the force of thespring 44 augments that of the spring 30 and the lamp is firmly held onlocking relationship and a good electrical contact between cap 2'l ofcontact 26 and the contact in the base of the lamp is insured.

It will be observed that the metal shell I9 01' the socket is adapted tobe electrically to one side of a source of potential through a bindingpost 46 in contact therewith and a wire 4'l connected to said bindingpost. The contact 26 is insulated from the metal socket shell bycircular shoulder 48 of insulating material forming a part of thesocket, and in fact is dead whenever the lamp house door is open. Theother side of the source of potential is connected to the contact 4| bya wire 49 and when the lamp house door is closed and the end of the stem28 is brought into engagement with the contact 4| the circuit of thelamp socket is completed. Consequently, the contacts 26 and Min eflfectconstitute a-switch for the circuit to the socket, and which switch isautomatically opened and closed when the lamp house door is opened andclosed, respectively; or stating it more broadly, a switch which is autm,matically opened and closed when the lamp socket is moved to and fromits lamp changing position, respectively. It will'thus be apparent thatwhen a lamp is inserted into the socket the same will not light andstartle the person performing the operation because the circuit to thesocket is automatically broken when the socket is moved to its lampchanging position.

It is pointed out that the present invention is not limited to use withsockets and'lamps having bayonet type locking connections, but is usefuland adapted for use with any socket into which 'a lamp is adapted to beinserted by,a straight thrust against the opposition of resilientcontact the resilient force of which forms a part of, or effects theoperation of a locking locking the lamp in the socket inserted thereuntoby a straight and lamp combination which'would meet these requirements,but which does not include a bayonet type locking arrangement, isdisclosed. in' pending U. S. patent application Serial No. 371,- 242,filed Dec. 23, 1940,-in the name of Joseph Mihalyi. In this socket andlamp combination referred to, a screw base lamp is adapted to beinserted into a socket by a straight thrust and in opposition to theresilience of a contact in the base of the socket. The lamp is locked inthe socket when one end of a bellcrank pivoted in the side of the socketengages a thread'on the lamp base and the engagement of the two beingafter once being mechanism for being thrust thereinto, said meansincluding a is decreased to lamp into the socket. The added feature ofautomatically breaking the circuit to the socket when the resilientforce of the socket contact permit an easy insertion of a lamp into thesocket and automatically closing .the circuit when the resilient forceof the contact is again increased after insertion of the lamp presentsadvantages which will be readily apparent to one skilled in the art.While the disclosed socket arrangement is particularly adapted for usewith motion picture apparatus as set forth it will be readily apparentthat the basic features of the same would be useful in otherapplications and could be readily applied to other apparatus.

Although I have shown and described certain specific embodiments of myinvention, I am,

fully aware that many modifications thereof are possible. My invention,therefore, is not to be limited to the precise details of constructionshown and described but is intended to cover all modifications comingwithin the scope of the appended claims.

Having thus described my invention, what I claim is new and desire tosecure by Letters Patent of the United Statesis:

1. In an apparatus of the type described the combination of a lampsocket into which a lamp is adapted to be inserted by a straight thrust,means for looking a lamp in said socket after member in said socketadapted to engage .a projecting portion on the base of the lamp afterthe same is fully inserted into the socket, a movable contact in thebottom of the socket against which the lamp base is adapted to abut,resilient means normally forcing said' contact into said socket andthereby to oppose insertion of a lamp into said socket and to oppose theremoval of thrust. Asocket the cooperating parts of said socket and lampbase from looking relationship when once estab-- lished, and means foralternately decreasing and increasing'the strength of said resilientmeans to facilitate changing a lamp in said socket and to firmly lockthe lamp in the socket after such a change, respectively. r

2. In an apparatus of the type described the combination of a lampsocket into which a lamp is. adapted to be inserted by a straightthrust, means for looking a lamp in said socket after being thrustthereinto, said means including a member in said socket adapted toengage-a projecting portion on the base of the lamp after the same isfully inserted into the socket, a movable contact in the bottom ofthesocket against which the lamp base is adapted to abut, a plurality ofresilient means adapted to normally force said contact into the socketand thereby oppose insertion of a lamp into said socket and to opposethe removal of the coopera in parts of said socket and lamp base fromlooking relationship when once established, and means for purposelyrendering certain of said resilient means ineiIective to facilitatechangin a lamp in said socket and for again rendering the same efiective-aitersuchachangetofirmlylockthelampin the socket. I

3. In an apparatus oi! the type described the combination or a lampsocket into which a lampthe-same has been fully inserted into thesocket,

a resilient contact in the base or said socket adapted to opposeinsertion of a lamp into said socket and to oppose the removal 01 thecooperating parts oi said socket and lamp base from locking relationshipwhen once established, said contact including an end extending throughthe base of said socket, means for movably mounting said socket to movefrom a lamp chan ngposition to a projecting position, a second resilientcontact locatedto be engaged and retracted by the extending end oi saidcontact whenj the socket is movedto its projecting position whereby itaugments the resiliency 01' said first contact to firmly lock the'lampin the socket, and cite disengaged by said contact when the socket ismoved to its lamp changing position whereby only the resiliency oi thecontact alone need be overcome in efiecting a change of lamp.

4. In an apparatus of thetype described the combination oi a lamp socketinto which a lamp is adapted to be inserted by a straight thrust, meansfor locking a lamp in said socket after. being thrust thereinto, saidmeans including a member in said socket adapted to engage a proi'ectingportion on the base 01' the lamp after the same has been fully insertedinto the socket, a resilient contact in the base or said socket adaptedto oppose insertion of a lamp into said socket and to oppose the removalof the-cooperating parts of said socket and lamp base from lockinrelationship when once established. said, contact including an endextending through the base of said socket. means for movably mountingsaid socket to move from a lamp changing position to a projectingposition, a second resilient contact located to be engaged and retractedby the extending end or said first contact when the socket is moved toits projecting position, where-. by it augments the resiliency of saidfirst contorce oithefirsttofirmlyholdthelampinlocked relation in thesocket. and adapted to be disengaged by said first contact when the dooris open.

whereby only the resilient force oi the first contact need be overcomein the operation of changing a lamp in the socket.

6. In a picture projector the combination with a lamp house, a pivoteddoor on said lamp house for opening and closing the same, a bayonet typelamp socket mounted on said door to move therewith and adapted toreceive a lamp having a complementary bayonet type base, a resilientcontact in the base ot. said socket adapted to engage the base of thelamp and including an end extending through the base of the socket. asecond resilient contact moilnted'on a fixed part of said lamp house ina position to be en aged and retracted bythe extending endoisaidfirstcontactwhen the door is closed, whereby the resilient iorceoi the second contact augments the tom of the first to firmly hold thelamp in locked relation lnthe socket,andadaptedtobedisengagedby said-first contact'when the door is open, whereby only the resilient forceof the first contact need be overcome in the operation of changin a lampin the socket, and means for automatically breaking and completing thecircuit to said socket when the lamp house door is opened and closed,respectively.

I; Ina picture projector the combination with a lamp house, a pivoteddoor on said lamp house for opening and" closing the same, a bayonettype lamp socket mounted on said door to-move therewith and adapted toreceive a lamp having a complementary bayonet type'base. means for,

electrically connecting the shell of said socket to one side'oi a sourceof potential, a resilient contactinthebaseoisaidsocketadaptedtoenlm thecontact in-theiamp base, said contact being normally insulated from thesource of potential and including anend extending through the base ofthe socket, a second resilient contact mountedonafixedpartotsaidiamphouseinapositicn to be engaged and retractedby'the extending end of said first contact when the door is closed,

. whereby the resilient force or the second contact tact to firmly lockthe lamp in the socket, and to be disengaged by said contact when thesocket is moved to its lamp changing Position whereby only theresiliency oi the contact alone need be overcome in efiecting a changeor lamp, and i 7 means for automatically interrupting the circuit tosaid socket when the sameiis moved to its lamp chan i position, 'and forautomatically completingsaid circuit whenthe socket isv-moved to itsprojecting position.

5. In a picture projector the combination with a lamp house,- a pivoteddoor on said lamp'house for opening and closing the same, a bayonet typelamp socket mounted on said door to move therewith and adapted toreceive a lamp having a complementary bayonet type base, a resilientcontact in the base of said socket adapted-teen age the base oi the lampand including an end extending through the base of the socket, a secondresilient contactflnounted on a fixed part 01'. said lamp house in aposition to be engaged and retracted by the extending end of said firstcontact when the door is closed, whereby the resiliaugments the force ofthe first to firmly the lamp in locked relation in the socketadaptedtobedisengagedbysaidfirstcon when the door is open, whereby onlythe resilient iorce oitbefirstcontactneedbeovercome the operation ofchanging a lamp in said second contact being connected to the other sideof the source of potential whereby said two contacts constitute a switchfor the circuit to the lamp socket.

8. In a picture projector the combination with a lamp house, a pivoteddoor on said lamp house for opening and closing the same, a bayonet typelamp socket mounted on said door to move therer with and adapted toreceive a lamp having a complementary-bayonet type base, means for outforce or the second contact augments the" electrically connecting theshell oisaid socket to one side of a source of potentiaL'a' pl contactextending through the bottom or. socket and adapted to move into and outoi socket, said plunger contact including a within the socket adapted toengage the contact in the base of a lamp inserted into said socket andan end extending below the bottom of said socket, a compression springsituated be-- tween the head or said plunger contact and the base oi."the socket and normally forcing said contact into said socket, a secondresilient contact mountedonafixedpartoisaidlemphcueein hold ,lllli tacta position to be engaged and retracted by the extending end of saidplunger contact when the door is closed, whereby the resilient force ofsaid second contact augments the force of said compression spring tofirmly hold the lamp in locked relation in the socket, and adapted to bedisengaged by said first contact when the door is opened, whereby onlythe force of said compression spring need be overcome in the operationof changing a lamp in the socket, said plunger contact 'normallyinsulated irom the source of potential, and said second contactconnected to the other side of said source of potential whereby said twocontacts constitute a switch for the circuit to the lamp socket. 1

- HENRY N. FAIRBANKS.

